Underlayment Calculator
How much underlayment for a floor? Pick foam, cork, felt, plywood or cement board and the floor area — get rolls or sheets with waste, and the note on which floors need which type.
5% for rolls (seams and cuts); 10% for sheets.
Underlayment for 120 sq ft
2 rolls — 126 sq ft to cover with 5% waste
Exact area: 120 sq ft (11.1 sq m). Each roll covers 100 sq ft, so 2 rolls cover 126 sq ft including waste. Underlayment is not optional for laminate and most vinyl plank — it levels small imperfections, deadens sound and, for foam types, adds a moisture barrier. Tile needs cement board, not foam.
Estimate. Roll and sheet coverage vary by brand — confirm the coverage printed on the product before ordering.
Formula used: Units = area × (1 + waste%) ÷ coverage per roll or sheet, rounded up.
How this estimate works: Underlayment is sold by the roll or sheet at a fixed coverage, so the tool adds a small waste allowance to the floor area (seams and cuts waste some of every roll) and divides by the coverage of the type you picked. Foam and cork come in rolls; plywood and cement board come in sheets — the unit changes with the type.
How the underlayment calculator works
Underlayment is sold by the roll or sheet at a fixed coverage, so the tool adds a small waste allowance to the floor area — seams and cuts waste some of every roll — and divides by the coverage of the type you picked. Foam and cork come in rolls; plywood and cement board come in sheets. Underlayment is not optional for laminate and most vinyl plank, and tile needs cement board, not foam. This is an estimate — confirm the coverage printed on the product.
Try next: Tile Calculator · Flooring Calculator · Laminate Flooring Calculator
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